Generally speaking, an electric plating operation is composed of a pretreating step, a plating step and a posttreating step. We, the inventors, have proposed an apparatus of the type, in which a work to be plated is accommodated in a plating chamber having a relatively small capacity and equipped with an electrode acting as an anode and in which an electric current is applied between the electrode and the work while making a plating liquid flow in that plating chamber thereby to effect the plating operation within a short time period. In this high speed plating apparatus, a work having been pretreated is supported by a holder so that it is transferred into the plating chamber, and the holder holds the work and advances, while holding it, into the plating chamber until the aforementioned work is held in the plating chamber. That holder not only supports the work but also has a function as a current supply terminal or a cathode for applying an electric current to the work. Since the holder has a portion existing in the plating chamber, as has been described in the above, the portion facing the plating chamber is also plated if the current is applied between the electrode and the work. As a result, when the plating operation is repeated for a long time period, the thickness of the plated layer on the holder surface is gradually enlarged until the holder is so large in diameter that its advance and retraction in and out of the chamber may be impeded or that it will fail to release the work.
Prior to the aforementioned plating operation, on the other hand, the work is accommodated in a back-electrolyzing chamber having a construction similar to that of the plating chamber, in which it may have its surface etched. Since, in that back-electrolyzing chamber, the polarities of the anodes and cathodes are reversed between the electrode and the work, the holder in this case has its circumference back-electrolized, i.e., etched thereby causing a fear that the holder may be worn by the aforementioned etching treatment after a long use.
Another problem is that the aforementioned electrode is formed in a cylindrical shape as a portion of the circumferential wall of the plating chamber so that it may be corroded by the plating liquid flowing therein, i.e., a highly corrosive electrolytic liquid.